I found on my hard drive a few documents from the disappeared site www.zenitcamera.com, I put them here at your disposal, as well as some pictures taken during tricky disassembly.
Identifying wires to desolder for removing the electric circuit of a Zenit Automat (EFCO electronics).Click on the image.
Zenit Automat schemasClick on the image.
Zenit 12XP schemasClick on the image.
Zenit TTL schemasClick on the image.